Gao Jiafeng, Zuo Songlin, Liu He, Jiang Qiwen, Wang Chenhao, Yin Huanhuan, Wang Ziqi, Wang Jie
Jiangsu Key Lab of Biomass Based Green Fuels and Chemicals, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China; Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, China.
Jiangsu Key Laboratory of Biomass Energy and Material, Nanjing 210042, China.
J Colloid Interface Sci. 2022 Oct 15;624:555-563. doi: 10.1016/j.jcis.2022.05.135. Epub 2022 May 25.
Silicon (Si) anode is the most promising alternative for next generation lithium-ion batteries (LIBs) owing to large theoretical capacity, low working voltage and abundant natural resources. However, tremendous volume change of Si during the (de)lithiation processes causes repetitive formation of solid electrolyte interphase (SEI) layers, loss of electrical contact and electrodes pulverization, limiting its commercial application. Herein, we fabricate an interconnected hollow Si-C nanospheres/graphite composite via a facile and scalable approach. Notably, hollow Si-C nanospheres and graphite are homogeneously combined by using the surfactants as surface modifiers of graphite and introducing carbon dioxide (CO) into magnesiothermic reduction reaction, resulting in the enhanced compatibility between hollow Si-C nanospheres and graphite, and the well-established electrical conductive network. The resultant Si-C nanospheres/graphite composite anode with carbon content of 59 wt% delivers a large reversible specific capacity of 662 mAh g and a high capacity retention of 65.7% at 0.5 A g after 200 cycles. Such excellent rate performance and superior cycling performance are attributed to high electrical conductivity and buffering effect of graphite, superior compatibility between hollow Si-C spheres and graphite, uniform distribution of both Si-C nanospheres with a unique hollow architecture and graphite flakes inside the composites and well-established interconnected electrical conductive carbon networks, which can effectively alleviate Si volume expansion and maintain good electrical contact during cycling. This strategy provides insights into designing Si-based anodes for practical LIBs.
硅（Si）阳极由于具有高理论容量、低工作电压和丰富的自然资源，是下一代锂离子电池（LIBs）最具潜力的替代选择。然而，硅在（脱）锂过程中巨大的体积变化会导致固体电解质界面（SEI）层的反复形成、电接触的丧失和电极粉化，限制了其商业应用。在此，我们通过一种简便且可扩展的方法制备了一种相互连接的中空Si-C纳米球/石墨复合材料。值得注意的是，通过使用表面活性剂作为石墨的表面改性剂，并将二氧化碳（CO）引入镁热还原反应中，中空Si-C纳米球和石墨得以均匀结合，从而增强了中空Si-C纳米球与石墨之间的相容性，并建立了良好的导电网络。所得碳含量为59 wt%的Si-C纳米球/石墨复合阳极在0.5 A g的电流密度下循环200次后，具有662 mAh g的高可逆比容量和65.7%的高容量保持率。如此优异的倍率性能和循环性能归因于石墨的高电导率和缓冲作用、中空Si-C球与石墨之间的优异相容性、具有独特中空结构的Si-C纳米球和石墨薄片在复合材料中的均匀分布以及良好建立的相互连接的导电碳网络，这些能够有效缓解硅的体积膨胀并在循环过程中保持良好的电接触。该策略为设计实用的锂离子电池硅基阳极提供了思路。
